were relative. In practically all such cases the genus is
relative, the individual not. Thus knowledge, as a genus, is
explained by reference to something else, for we mean a knowledge
of something. But particular branches of knowledge are not thus
explained. The knowledge of grammar is not relative to anything
external, nor is the knowledge of music, but these, if relative
at all, are relative only in virtue of their genera; thus grammar
is said be the knowledge of something, not the grammar of
something; similarly music is the knowledge of something, not the
music of something.

Thus individual branches of knowledge are not relative. And it is
because we possess these individual branches of knowledge that we
are said to be such and such. It is these that we actually
possess: we are called experts because we possess knowledge in
some particular branch. Those particular branches, therefore, of
knowledge, in virtue of which we are sometimes said to be such
and such, are themselves qualities, and are not relative.
Further, if anything should happen to fall within both the
category of quality and that of relation, there would be nothing
extraordinary in classing it under both these heads.

Section 3

Part 9

Action and affection both admit of contraries and also of
variation of degree. Heating is the contrary of cooling, being
heated of being cooled, being glad of being vexed. Thus they
admit of contraries. They also admit of variation of degree: for